150mm CF. The C lenses have the aperture and shutter speed locked together unless you depress a lever. A real PITA. Keep an eye on KEH.com for a CF. I got a "bargain" rated lens from them for $565 and to this day cannot figure out why it was rated as such. There was some MINOR brassing around the lenshood bayonet lugs, but the appearance, shutter and glass are otherwise flawless. And it comes with a 10 day return period with no questions asked. They also have some sort of warranty, I believe, but I've never needed it.